KR20000059295A - Method of preparing for tungsten alloys on substrate using electroless plating as a anti-corrosion medium - Google Patents

Abstract

PURPOSE: A method is provided to accomplish an improved a surface hardness and corrosion resistance of a metallic base metal. CONSTITUTION: A method comprises the steps of cleaning a surface of a metal such as an aluminum or an aluminum alloy by degreasing and acid cleaning method and simultaneously forming a zinc substitution film, performing an alloy plating utilizing an alloy constituted by Ni and W, and performing a finishing plating utilizing either composition of Pd, Ni, W or Ni and W. Thus, a tungsten alloy is evenly coated onto the surface of the base metal, thus obtaining an improved surface hardness and corrosion resistance. In addition, improvements in mechanical, chemical and physical properties of the base metal can be obtained.

Description

Plating method of tungsten alloy to improve the corrosion resistance of metals TECHNICAL MODE OF TUNGSTEN ALLOYS ON SUBSTRATE USING ELECTROLESS PLATING AS A ANTI-CORROSION MEDIUM

An object of the present invention is to provide a plating method that provides a mechanical, physical and chemical properties superior to the base material by coating a dissimilar metal on the surface of the Al or SUS base material, and particularly, excellent corrosion resistance in a strong acid atmosphere of chlorine, fluorine or bromine An object of the present invention is to provide a coating technology for introducing a coating layer having a capability to a base metal surface.

Al is a light, ductile, easy-to-machine material, and has a wide range of applications due to its many advantages. On the other hand, Al in the pure state of the alloy has the disadvantage of having a weak mechanical and chemical properties, and various methods have been used to compensate for this. Among these methods, alloy refining is used to maintain the state of the alloy added with silicon, magnesium, copper, manganese, etc. during the refining process of aluminum base to improve the mechanical strength and to improve the corrosion resistance against acid or alkali, For surface modification, it has been used by surface treatment oxidation method (Anodizing) which is electrolytic oxidation treatment in chromic acid, acetic acid, sulfuric acid bath.

There are six major types of stainless steel (austenite, ferrite, multensite, two-phase SUS, PH-SUS, ferrite / austenite), and they contain chromium (18-8, 18, 13, 25-5). % Ni) and subdivided according to the type of tissue. Chromium contained in stainless steel forms chromium oxide film (Cr ₂ O ₃ ) by reaction with oxygen in air or in solution. In case of such chromium oxide film, corrosion resistance is improved by suppressing corrosion by cathodic formation due to passivation process. It will function. This function of chromium serves to enhance the corrosion resistance of stainless steel.

As described above, the surface oxidation treatment method for corrosion resistance on the surface of Al or Al alloy can be said that the effect is much better than the Al base material itself. As it is 20 ~ 30㎛ thick film or porous structure, there is a high risk of exfoliation by exposing the base material to corrosive tendency.The film obtained from Cr acid bath is dense and smooth, but it is thin film of less than 10㎛, so it is easy to be worn by mechanical friction. The film obtained by the bath has a high hardness and can be colored, but since it is also a thin film, it is easily worn by physical friction. Therefore, none of the above-described film forming methods have a proven corrosion resistance, and the application to unit processes in pharmaceutical, oil refining, and semiconductor fields, in which acid application of gas is mostly applied, has many problems. Therefore, the present invention is to improve the acid resistance compared to the conventional surface treatment method by finishing the tungsten (W) electroless plating and palladium (Pd) plating after the pre-treatment work and Ni-buffered plating on the surface of the existing Al base material.

As described above, stainless steel maintains its corrosion resistance by passivation treatment due to the mixed chromium (Cr) oxide, but is not limited to bromine (Br), chlorine (Cl ₂ ), fluorine (F), and the like. In an acidic environment, local corrosion such as formula, grain boundary corrosion, stress corrosion, etc. are induced, resulting in the use system as a corrosion resistant material. In the meantime, various surface treatment methods such as fluororesin coating and enamel glass coating have been implemented as a method of improving the corrosion resistance of the base material, but additional costs are caused by peeling of the coating layer due to the difference in coefficient of thermal expansion between the base material, resin, and inorganic ceramic. There are some difficulties in solving such corrosion resistance problems. Therefore, in the present invention, in order to compensate for the above-mentioned disadvantages of the prior art and solve the fundamental problem of the example, the tungsten (W) electroless plating and palladium (Pd) plating after the Ni-buffered plating followed by the pretreatment operation and the buffer plating treatment on the stainless base metal surface In order to improve the acid resistance, compared to the existing stainless steel surface treatment method.

[Means to solve the problem]

After degreasing and electrolytic degreasing of metals such as Al or Al alloys, the surface is cleaned by pickling (hydrochloric acid, nitric acid), and a tin-substituted film is formed, followed by Ni (addition of 3% phosphorus) and W. After plating the alloy with a buffer and buffering it, depending on the application process, Pd, Ni (5% phosphorus), W or Ni (5% phosphorus), W is coated and finished at 300 ° C. The heat treatment improved the physical properties of the film.

After degreasing and electrolytic degreasing of the stainless steel base, pickling (hydrochloric acid, nitric acid) is used to remove the passivation film formed on the surface of the stainless steel, followed by alloy plating of zinc, tin, and Ni, followed by Ni, W, Finishing by plating with a composition of Pd or Ni, W and heat treatment at 350 ° C. improved the physical properties of the film. Degreasing, electrolytic degreasing, acid washing, and the formation of zinc and tin replacement coatings serve to clean the substrate surface and improve adhesion to prevent peeling.

Ni- and W-alloy plating containing 5-15% W and 3-5% P is performed in buffer plating, and the corrosion resistance against acid is stronger than that of conventional Ni plating, and the corrosion resistance is enhanced in strong acid atmospheres such as hydrofluoric acid, acetic acid, and hydrochloric acid. In addition, tin, zinc, Ni alloy plating is used as a corrosion-resistant plating, and between the base material and the finish plating is used to improve the corrosion resistance by the interaction. Tin, zinc, and Ni alloy platings are stronger than Ni plating, and have a strong moisture resistance. When W is vacant with other alloys such as Ni, W becomes vacant in the range of about 2 to 50%. Ni, W alloy or Ni, W, Pd alloy plating thus formed shows strong corrosion resistance, especially under chlorine or fluorine-based environments. After plating the strong corrosion-resistant material W as an alloy, the vacancy of Pd having more excellent corrosion resistance is contained in the plating film to act as a corrosion resistant material. Further, as described above, by laminating films having respective characteristics, a plating film having high corrosion resistance is formed. Deposition of Pd determines the action according to the application and use of the film, and controls the hardness and physical properties of the film according to the composition change of the plating bath and the heat treatment conditions.

Example 1

Hereinafter, embodiments of the present invention will be described. However, the following examples are only for illustrating the present invention and the present invention is not limited by the examples. Al alloy containing Si, Fe, Cu, Mn, Mg, Zn, Cr, Ti, Al (for example, degreasing and etching acid cleaning on KS standard Al alloy number 1080) to clean the surface , And double-substitute tin by SUPER ZII (trade name of KIZAI Co., Ltd.), and buffer plating for about 10 minutes under the conditions shown in Table 1 below.

Nickel Buffer Plating Bath Components and Process Conditions Drug composition Drug amount NiBr ₂ · 3H ₂ O 60 to 70 g / l Na ₂ WO ₄ · 2H ₂ O 40 to 60 g / l (NH ₄ ) ₂ C ₆ H ₅ O ₇ 5 to 20 g / l Na ₃ PO _{4 12} H ₂ O 50 to 150 g / l Control item Control condition PH 6.5 to 7.5 Process temperature 50 ~ 60 ℃ Current density 2-5A / ㎠ time 5 to 10 minutes

After the above buffer plating, corrosion-resistant plating is performed under the electrolytic conditions shown in Table 2 below.

Corrosion Plating Bath Components and Process Conditions of W Alloy Drug composition Drug quantity NiBr ₂ · 3H ₂ O 200 to 250 g / l SnBr ₂ 40-50 g / l NH ₄ HF 5 to 20 g / l NaF 20-50 g / l Control item Control condition PH 6.5 to 7.5 Process temperature 60 ~ 80 ℃ Current density 3 to 5 A / ㎠ time 15 minutes

After the corrosion-resistant plating and water washing were uniformly performed on the surface of the buffer plating, finish plating was further performed under the electrolytic conditions shown in Table 3 below. The finish plating was divided into Bath A without palladium fluoride and Bath B with palladium fluoride, depending on the corrosion environment used.

Pd-based finish plating bath components and process conditions Drug composition Bath A (g / l) Bath B (g / l) NiSO ₄ 7H ₂ O 20 30 to 60 Na ₂ WO ₄ · 2H ₂ O 80 50-70 _{C 6 H 8 O 7 · H} 2 O 70 70-80 (CF ₃ CO ₂ ) ₂ Pd - 20-30 Control Item Control Condition Control Condition PH 6 to 8 6 to 8 Process temperature 70 ~ 80 ℃ 70 ~ 80 ℃ Current flow 5-15A / ㎠ 5-15A / ㎠ time 40 to 60 minutes 40 to 60 minutes

The product obtained by plating has a coating thickness of 20 to 30 µm, and the composition of the alloy plating performed under electrolytic conditions of Bath B using palladium trifluoride acetate shown in Table 3 as a composition is as shown in Table 4 below. The thickness of the plating can be arbitrarily changed by setting the corrosion resistance limit corresponding to the use and the corrosion environment used.

Ni 50 to 60% P 3-5% W 30 to 45% Sn 0.5 to 2% Pd 5 to 20% Zn 0.01 to 0.5%

Experimental Example 1

In this experimental example, an alloy plated Al plate was placed in a commercial 36% hydrochloric acid solution and deposited at room temperature for 48 hours. In order to compare the experimental results, the Al plating was carried out under the same electrolytic conditions as in Table 1, and the Al plating was carried out under the same electrolytic conditions as in Table 1. It was deposited under the same conditions. The results are shown in Table 5 below.

Test Psalm Test result Al Corrosion occurs at the same time as deposition Ni plating 10㎛ on Al Desquamation of the membrane occurs, local corrosion progresses Plating finish in Bath A No exfoliation of the membrane, local corrosion progression Plating finish at Bath B No delamination of the membrane, no corrosion progress.

Experimental Example 2

The alloy plated Al plate obtained by this experiment was placed in a desiccator in which chlorine GAS was generated, and it was left for about 72 hours under 90% humidity and normal temperature environment. In order to compare the experimental results, Al and Al were plated with Ni with a thickness of 10 µm in the same manner as in the previous conditions, or buffer plating under the electrolytic conditions of Table 1 above. It was placed under the same conditions. The results are shown in Table 6 below.

Test result Al Front rust generation Ni plating 10㎛ on Al 70 to 80% of surface white and green spots rust Plating finish in Bath A No swelling, no local corrosion Plating finish at Bath B No bloat, no rust spots over

Experimental Example 3

The alloy plated Al plate obtained by this experiment was placed in a transparent plastic container containing 48% hydrofluoric acid aqueous solution, and left at a humidity of 90% or more at room temperature for about 72 hours and placed under hydrogen fluoride gas. In order to compare this, Al plate and Al plate with Ni thickness of 10 μm were applied in the same manner as before, buffer plating under the electrolytic conditions of Table 1 above, and corrosion-resistant plating under the electrolytic conditions of Table 2 above. One was placed under the same conditions. The results are shown in Table 7 below.

Test result Al Severe corrosion due to full powder Ni plating 10㎛ on Al 90% white rust Plating finish in Bath A Some 5% localized corrosion Plating finish at Bath B No bloat, no rust spots over

Example 2

Al alloys (for example, KS standard Al alloy No. 2024) having alloy Al of Si, Fe, Cu, Mn, Mg, Cr, Zn, Zr and TiO as a composition component are all subjected to the same process as in the aforementioned embodiment. After degreasing and etching acid cleaning to clean the surface, zinc substitution, for example, double substitution treatment by SUPER ZII (KIZAI tradename), buffer plating under the electrolytic conditions shown in Table 1, Table 2, Table 3 , Corrosion-resistant plating and finish plating were carried out sequentially.

Experimental Example 4

About the alloy plating obtained in the present Example, the corrosion resistance experiment shown in the previous Experimental Examples 1-3 was carried out similarly to the alloy plating shown in Example 1 above. Also in the present Example, similarly to Example 1 mentioned above, the favorable experimental result as shown in Tables 5, 6, and 7 was obtained.

Example 3

Al alloy (eg JIS standard Al alloy No. 5005) containing Si, Fe, Cu, Mn, Mg, Cr, Zn, Ti, and Al as a composition component is also degreased and etched acid washed in the same manner as in Example 1 described above. The surface was cleaned and then subjected to a double substitution treatment by zinc substitution (for example, SUPER ZII (KIZAI tradename)), and buffered, intermediate, and finish plating were performed as shown in Tables 1-3.

Experimental Example 5

The alloy plating obtained in this example was subjected to the corrosion resistance experiments shown in Experimental Examples 1 to 3 in the same manner as the alloy plating shown in Example 1 above. Also in this example, good experimental results as shown in Tables 5, 6 and 7 were obtained in the same manner as in the above-described examples.

Example 4

Al alloys (for example, KS standard Al alloy No. 7075) containing Si, Fe, Cu, Mn, Mg, Cr, Zn, Ti, and Al were also subjected to the surface treatment in the same manner as in the above-described examples. .

Experimental Example 6

The alloy plating obtained in this example was subjected to the corrosion resistance experiments shown in Experimental Examples 1 to 3 in the same manner as the alloy plating shown in Example 1 above, and the good experimental results as shown in Tables 5, 6 and 7 were obtained. Got.

Example 5

Si, Fe, Cu, Mn, Mg, Cr, Zn, alloys of Zr and TiO, Ti, Al, Al alloys as a base material, alloys of Si and Fe, Cu, Mn, Mg, Zn, Al For example, KS standard Al alloy No. 7N01 was also surface-treated by the same procedure as in the above-described embodiment.

Experimental Example 7

The alloy plating obtained in this example was subjected to the experiments shown in Examples 1 to 3 above, and as a result, good experimental results as shown in Tables 5, 6 and 7 were obtained. In the above embodiment, after the buffer plating and the corrosion plating treatment, the finish plating can be carried out to obtain a corrosion-resistant plating film, but the final plating at the final stage does not include the electrolytic conditions of bath B including Pd shown in Table 3. Whether or not the electrolytic condition is used in Bath A depends on the intended use of the product and the corrosion environment used.

Example 6

After cleaning the surface of 18Cr-8Ni stainless steel sheet by degreasing and pickling, strike plating is performed for about 3 to 5 minutes under the electrolytic conditions shown in Table 15 below, followed by buffer plating. This activation method is not necessarily limited to the cathode electrolysis method, and sometimes the anode electrolysis is performed in parallel.

Drug composition Drug quantity NiBr ₂ · 3H ₂ O 200 to 250 g / l SnC _l2 40-50 g / l NH ₄ HF 5 to 20 g / l HCl 20-50 g / l Control item Control condition PH 6.5 to 7.5 Process temperature 60 ~ 80 ℃ Current density 3 to 5 A / ㎠ time 5 minutes

After strike plating, water washing was performed and corrosion-resistant plating by tin, Ni, and alloy plating was performed under the electrolytic conditions shown in Table 16 below. Tin Ni alloy plating was used as corrosion plating because it shows strong corrosion resistance in a chlorine-based environment.

Drug composition Drug quantity NiBr ₂ · 3H ₂ O 200 to 250 g / l CoC _{l26H 2} O 40-50 g / l NH ₄ HF 5 to 20 g / l NaF 20-50 g / l Control Item Control Condition PH 6.5 to 7.5 Process temperature 60 ~ 80 ℃ Current density 3 to 5 A / ㎠ time 15 minutes

After corrosion-resistant plating was washed with water, finish plating was performed under the electrolytic conditions shown in Table 10 below. Finish plating was performed by dividing bath C which did not contain Pd and bath D which contained Pd according to the environment to be used. Plating by bath D was 20㎛ thickness and the alloy plating composition is shown in Table 11.

Drug composition Bath A (g / l) Bath B (g / l) NiSO ₄ 7H ₂ O 20 30 to 60 Na ₂ WO ₄ · 2H ₂ O 80 50-70 _{C 6 H 8 O 7 · H} 2 O 70 70-80 (CF ₃ CO ₂ ) ₂ Pd - 20-30 Control Item Control Condition Control Condition PH 6 to 8 6 to 8 Process temperature 70 ~ 80 ℃ 70 ~ 80 ℃ Current flow 5-15A / ㎠ 5-15A / ㎠ time 40 to 60 minutes 40 to 60 minutes

Ni 60 to 65% Sn 1 to 2% W 35-40% Co 0.5 to 0.7% Pd 1 to 3% P 0.3 to 0.5%

Experimental Example 8

Three of the strike plates in the buffer plating under the conditions shown in Table 8 were closely tested. One was a bending test after heating at high temperature, the second was a hardness test rubbing the cut surface, and the third was a bending test by being bitten by a vice. The first one had no peeling at the part where swelling was seen in the appearance. Both the second and third had no peeling. As shown in the destruction test, it showed strong adhesion.

Experimental Example 9

In order to compare the alloy plated stainless steel sheet obtained in Example 6, it was immersed in an aqueous solution of concentrated hydrochloric acid for 148 hours in an ambient temperature environment such as 18Cr-8Ni stainless steel sheet and 18Cr, 12Ni-2.5Mo stainless steel sheet. The results are shown in Table 12 below.

Test Psalm Test result 18Cr-8Ni stainless material 50 ~ 70% rust occurrence on the surface 18Cr, 12Ni-2.5Mo Stainless Steel Sheet 20% rust on the surface Bath A No plating film expansion, no surface rust. Bath B No plating film expansion, no surface rust.

Experimental Example 10

In order to compare the alloy plated stainless steel sheet obtained in the present embodiment, 72 hours were deposited in a desiccator having a humidity of 90% or more where chlorine gas is generated in an ambient temperature environment such as 18Cr, Ni stainless steel sheet and 18Cr, 12Ni-2.5Mo stainless steel sheet. It was. The results are shown in Table 20 below.

Test Psalm Test result 18Cr-8Ni stainless material Surface rust occurrence rate No. 5 or less 18Cr, 12Ni-2.5Mo Stainless Steel Sheet Surface rust occurrence rate 6 to 7 Bath A No plating swelling, surface rust incidence No. 8 to 9 Bath B No plating swelling, surface rust incidence No. 10

Experimental Example 11

In order to compare the alloy plated stainless steel sheet obtained in this example, a 48% hydrofluoric acid solution, such as 18Cr, Ni stainless steel, and 18Cr, 12Ni-2.5Mo stainless steel, was placed at the bottom of a transparent plastic container in which hydrogen fluoride gas was generated. Time was deposited. The results are shown in Table 21 below.

Test Psalm Test result 18Cr-8Ni stainless material Rust on the surface all over, ratio No. 5 or less 18Cr, 12Ni-2.5Mo Stainless Steel Sheet Surface 20% rust generation, rate No. 5 to 6 Bath A Surface rust occurs. Ratio No. 7-8 Bath B Surface rust occurs. Ratio No. 9-10

Example 7

As described above, 18Cr, Ni stainless steel sheet, 18Cr, 12Ni-2.5Mo stainless steel sheet, and 18Cr stainless steel sheet were also subjected to degreasing, acid washing, strike plating, corrosion resistance plating, and finish plating in the same manner as in Example 6. A plated film having a thickness of 20 µm for 18Cr and 8Ni stainless steel sheets and a thickness of 15 to 20 µm for 18Cr and 12Ni-2.5Mo stainless steel sheets and a thickness of 10 to 15 µm for 18Cr and stainless steel sheets was obtained.

Experimental Example 12

Also about the alloy obtained by Example 7, the corrosion resistance experiment was performed as mentioned in Experimental Examples 1-7 mentioned above. The results obtained the same results as Bath A and B in these experimental examples, and proved to have good corrosion resistance under chlorine-based and fluorine-based environments.

Test Psalm Test result 18Cr-8Ni stainless material Rust on the surface all over, ratio No. 5 or less 18Cr, 12Ni-2.5Mo Stainless Steel Sheet Surface rust occurrence, rate No. 6 to 7 Bath F No plating bulge, surface rust rate No. 8 to 9 Bath G No plating bulge, surface rust rate No. 10

It is an object of the present invention to provide a plating method having good corrosion resistance by applying multilayer alloy plating on the surface of a metal material.

1 is a process progress diagram for W electroless plating of Al and SUS base materials to be achieved in the present invention.

Figure 2 is a schematic diagram showing a method for testing the corrosion loss for the specimen made by the coating method and the method (bare matal-Al, SUS) presented in the present invention.

Figure 3 is a graph showing the corrosion loss over time after the immersion test of the coated SUS316L specimen and the uncoated SUS316L specimen in 10% aqueous hydrochloric acid solution by the method proposed in the present invention.

Figure 4 is a graph showing the corrosion loss over time after exposing the coated SUS316L specimen and the uncoated SUS316L specimen in 100% hydrochloric acid gas by the method proposed in the present invention.

Figure 5 is a graph showing the corrosion loss over time after immersing the coated SUS316L specimen and the uncoated SUS316L specimen in 2.5% HF solution by the method proposed in the present invention.

Figure 6 is a graph showing the corrosion loss over time after exposing the coated SUS316L specimen and the uncoated SUS316L specimen in 100% HF gas by the method proposed in the present invention.

After cleaning the surface of the metal material by degreasing, acid washing, etc., after performing buffer plating, it is performed as finish plating regardless of the plating of Pd, Ni, W or Ni, W according to the use purpose.

According to the invention of claim 1, after the surface is cleaned by degreasing, pickling, or the like, it is easy to plate by forming a zinc film, the adhesiveness is improved, and the peeling is difficult. Forming a film on the metal by three layers of plating showed the effect of improving the corrosion resistance.

The invention of Claim 2 has shown the effect which enables the plating of the stainless surface which was difficult conventionally, prevents corrosion of stainless steel formula, stress corrosion fragments, etc., and improves corrosion resistance.

The invention of Claims 1 to 2 has an effect that it can be used as a chemical manufacturing equipment, a material or a semiconductor manufacturing equipment used material which strongly requires chemical resistance by forming a multilayer of an alloy having good corrosion resistance.

Claims (2)

Degreasing and pickling metal materials such as aluminum or aluminum alloys cleans the metal surface of aluminum or aluminum alloys, and forms zinc-substituted coatings, followed by alloy plating with Ni and W. After alloy plating with Ni and W on the surface, corrosion plating was performed, and then alloy plating was performed as finish plating regardless of Pd, Ni, W, or Ni or W according to the intended use. Method of W alloy plating characterized by Degreasing and pickling stainless steel base material removes the passivation film formed on the surface of stainless steel, and then alloy plating with tin and Ni composition, and either Ni, W, Pd, or Ni, W according to the intended use. W alloy plating method characterized in that the alloy plating is performed as the finish plating regardless of the plating.